Although I have only had a handfull of M74 (no B) models cross my benches, none had an unusual highspeed needle.
Yet here we have one with a stepped tip like those funny bombsight carbs for Ks or whatever ( on left in attachment).
But it has the Big Twin knob.
By visual inspection, the seat in the casting looks ordinary.
Can anyone add any certain information about this unusual needle?
Thanks in advance,